Study Suggests Rural Households Have Lower Risk of Crohn's and Colitis Development

A recent study suggests that children and adolescents who grow up in rural households may have a lower chance of developing inflammatory bowel disease (IBD). The study was conducted and published by the Canadian Gastro Intestinal Epidemiology Consortium, the Institute for Clinical Evaluative Sciences, and the Children's Hospital of Eastern Ontario.

Dr. Eric Benchimol, a lead author in the study, a pediatric gastroenterologist at the Children's Hospital of Eastern Ontario, and a scientist at the Institute for Clinical Evaluative Sciences says that the findings prove that children seem to be protected against developing IBD when they live in rural households. The value of the protective quality seems to increase with children under 10 years old and children who were raised in rural households for the first five years of their lives. Dr. Benchimol says that these revelations are especially important because the rate of young children who are diagnosed with IBD has increased dramatically over the last two decades. Dr. Benchimol also states the importance of pointing out the role that environmental risk factors play in determining who is at a greater risk for developing IBD due to factors that may predispose people to developing IBD.

Crohn's disease and ulcerative colitis are two of the most common conditions of IBD. IBD causes inflammation in the digestive tract that can lead to several unfortunate issues, including weight loss, stomach pains, bloody stool, and chronic diarrhea.

The study, which was published on July 25, 2017, in the American Journal of Gastroenterology medical journal identified only 6,662 patients who had IBD and were living in rural households and 38,905 patients who had IBD and were living in urban households between the year 1999 and the year 2010, with a total of 45,567 IBD patient participants in the study. The urban households reside in the Canadian provinces Ontario, Nova Scotia, Manitoba, and Alberta. The study revealed an overall IBD incidence in rural households of 30.73 per 100,000 person-years and an overall IBD incidence in urban households of 33.16 per 100,000 person-years.

Those in the medical community have known for some time that environmental factors can increase the risk of developing IBD along with certain genetic factors. This study may suggest how important exposure to environmental factors during the early years of life may be in determining the risk of developing IBD. Benchimol claims that the exact role that these environmental factors play warrant further study.

Canada has one of the highest rates of people living with IBD in the world with about 233,000 people dealing with the immune-mediated disease on a daily basis. The rates of people being diagnosed with IBD seem to be rising steadily in Canada and the reason is not fully understood. The researchers involved in this study believe that perhaps a life growing up in a rural household with exposure to different environmental factors could create changes in the intestinal microbiome that decrease the risk of developing IBD.

Less Risk of Inflammatory Bowel Disease in Warmer Climates

Another study shows that people who live in warmer climates may also have a decreased chance of developing IBD, especially in adults over the age of 30. The study, which was published in the GUT medical journal in 2012, supports earlier research conducted in Europe and could eventually lead to new treatment and preventative measures.

While genetic factors that may contribute to people developing IBD have already been identified and studied, the exact causes behind IBD are still largely unknown. The researchers behind this study suggest that if a person has a low or moderate genetic risk of developing IBD that certain factors of environment and lifestyle may also play key roles in a person's overall risk factor.

The findings in the research study were based on data that was pulled from two studies that were completed to track the long-term health of nurses, called "Nurses' Health Study 1" from 1976, and "Nurses' Health Study 2" from 1989.

Both of the nurses' health studies included various information on the area where people lived at birth between 15 years old and 30 years old and whether or not they were diagnosed with IBD up until the year 2003. The 238,000 participants, who ranged from age 25 and age 55, were asked to complete mailed information reports every two years. As part of the research, none of the original participants had IBD at the time that they were asked to enroll in the study.

In 1992 the researchers began recording the residence of around 176,000 women and by 2003, 257 of the women surveyed had received a diagnosis of Crohn's disease while 313 of the women surveyed had received a diagnosis of ulcerative colitis. The women were categorized based on where they resided within the U.S. The categories were broken down as follows: Pacific, Mountain, Central, and Eastern. The regions of residence were broken down further based on whether or not the women lived in northern, middle, or southern regions.

The researchers of this study found that women who lived in colder, northern regions were more likely to develop IBD than women who lived in warmer regions and women who were 30 years old or older were at an even higher risk than women younger than 30.

The research was broken down to show that women who lived in warmer, southern regions had a 52 percent less chance of being diagnosed with Crohn's disease and a 38 percent reduced chance of developing ulcerative colitis by the time they were 30 years old when compared to the participants who lived in colder, northern regions.

Furthermore, according to the study, smoking had no influence on the participants' risk of developing IBD, which is contrary to previous assumptions.

The authors of this research study suggest that one of the main explanations behind the difference in the risk of developing Crohn's disease and ulcerative colitis based on whether participants resided in the northern regions or the southern regions may be partly due to changes in the amount of exposure that the participants had to sunlight and UVB radiation. Both sunlight and UVB radiation are greater in southern regions and UV radiation is known to be one of the largest contributors to the production of plasma vitamin D. There has already been ample research to support the idea that vitamin D plays a key role in helping to control immunity and regulate the body's natural inflammatory response.

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